A seismic shift for mineral exploration

Image: HiSeis.

Exploration companies are searching for new methods to unlock the next wave of mineral deposits. A technology proving valuable in this pursuit is 3D seismic surveying.

Exploration activity is increasing across the hard rock mining sector. At the same time, reserves are becoming increasingly difficult to unlock as deposits change.

With the mining industry settling into a more vibrant environment, many companies have responded by expanding their exploration budgets.

Australian Bureau of Statistics (ABS) figures reflect these moves, showing a 4 per cent rise in exploration in the September 2018 quarter to push spending to its highest level in five years.

Western Australia’s hard rock miners guided this growth as spending in the gold sector surged.

Exploration for gold is on track to grow even further this year after several leading companies declared larger budgets. Northern Star Resources, for example, increased its exploration budget by a third to $60 million in the 2019 financial year.

Evolution Mining has also boosted its planned exploration spend from $32 million to up to $55 million.

The increase in spending is a welcome sign for the mining industry, but it doesn’t remove the challenge of declining grades, resource depletion and deposits becoming deeper.

To overcome this, mining companies are considering different methods, including seismic surveying, a technique that has emerged in hard rock exploration over the past decade.

Western Australian-focused hard rock companies, in particular, have embraced 3D seismic surveying to unlock deeper reserves and for exploration under cover.

Perth-based HiSeis, a company created by Curtin University professors Anton Kepic and Milovan Urosevic in 2009, remains the only commercial provider of the technology for mining.

The HiSeis team has overcome sceptics of seismic surveying who criticised the technology as a tool that is only effective for exploration in the oil and gas industry.

Curtin University developed tools and techniques that enabled the application of the technology for hard rock exploration, removing the limitations linked with deeper resources and exploration under cover.

Seismic surveying’s reputation in mining has strengthened in recent years following exploration campaigns by the likes of Northern Star and Evolution, as well as nickel-focused Independence Group (IGO).

HiSeis’ technique has been deployed by each of these companies to better define and interpret the geological features of their sites.

Chief executive officer Joe Dwyer, who joined HiSeis in 2013, says there has been a shift in the mining industry’s attitude towards seismic surveying for exploration off the back of these campaigns.

“I have seen a step change over the last couple of years in that the technique is at least getting some credibility,” Dwyer tells Australian Mining.

“Some of the detractors in the early days would talk of myths that seismic can’t image deep structures, or can’t image thin or steep structures. Typically, these are the origin of gold deposits that are hosted within thin vein systems.

“The success we’ve had recently firstly shows that you can image deep structures, and secondly we have learnt something with the alteration associated with the gold mineralisation. We can image that and that is really useful for gold mining.”

Jerry Giannakis on site for HiSeis.

 

Dwyer says long-time users of 3D seismic surveying, such as Northern Star, Evolution and IGO, have been rewarded by taking risks with a new technique.

Northern Star, for example, made the Zodiac discovery at the Jundee mine in 2017 by drilling targets taken from a 3D survey after believing in the technology for many years.

“Typically the companies that have senior management or a culture of being innovative are the ones more willing to accept a new idea, and seismic in mining is a new idea,” Dwyer says.

“That is a common thread I find; it’s the miners that have a leader, MD or chairman who is prepared to do something different and not just keep with the paradigm.

“Northern Star took a chance and we have done half a dozen projects for them in different gold mines.”

IGO was another early adopter of seismic, as far back as the days before HiSeis with Curtin University. HiSeis acquired a 3D seismic survey of the Nova nickel-copper-cobalt operation for IGO in early 2017.

Initially, IGO wanted to establish a better understanding of how useful it would be for the company to acquire 3D seismic data.

The companies finished up performing the largest-ever 3D hard rock seismic survey at Nova, which HiSeis delivered to IGO in July 2018 six months after starting work on it.

IGO exploration project manager Paul Polito says the company considers Nova a strong candidate for seismic surveying because its mineralisation is not limited to the near surface.

“It’s mostly under cover and therefore we needed the latest technology available to go deep,” Polito says.

“We believe we can mine Nova-like mineralisation to at least two kilometres depth underground and there is no other technology more superior at the moment than HiSeis 3D seismic surveying that allows us to target hard rock mineralisation at those sorts of depths.”

IGO has also acquired 3D seismic data for its Tropicana gold joint venture (with Anglo Gold Ashanti) and the Long nickel operation.

The company is confident the success of the 3D surveys at Tropicana and Long bodes well for its development plans at Nova and around the overall mining lease.

“The more we drill the better we understand that data set,” Polito says. “What makes it appealing is the level of geological detail that we can obtain at considerable depths. That kind of information cannot currently be obtained using any other method.”

IGO has emerged as one of the trailblazers of 3D seismic surveying since experimenting with a Curtin University prototype at the Long project 10 years ago.

Polito says the seismic surveys have also proven to be good value for money given the geological and structural information it has provided in a 3D environment.

“This information to collect through conventional drilling would be cost prohibitive. We are confident that this technology and applying the scientific approach in a scientific way will lead to additional Nova-like deposit discoveries,” Polito says.

“Traditionally, many explorers believed using seismic for hard rock would be too complicated, but we believe that as we increase our understanding of using 3D seismic and increase our confidence in how we use the data, then it will become more commonly used in brownfields exploration.”

HiSeis has managed to capture the attention of the mining industry with these breakthroughs.

A group of industry executives, mining services company Ausdrill and other professional investors joined forces to buy a majority ownership in the company last year.

The change in ownership reflected HiSeis’ growth plans. It has helped support the company’s international expansion and consolidate its position as a hard rock seismic provider.

These investors are hoping to push HiSeis to the next level, as the company wants to do with the exploration sector using its technology.

This article also appears in the February edition of Australian Mining. 

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